Synthesis of N, N'-1, 2-vinylidene and 1, 2-phenylene bridged

Synthesis of N,N'-1,2-vinylidene and 1,2-phenylene bridged porphyrins. X-ray crystal and ... Publication Date: May 1987 ... Chemistry Letters 2001 (1)...
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J. Am. Chem. SOC.1987, 109,2946-2955

2946

ions,12amany of which incorporate biologically relevant sulfurdonor ligands), and D3+ ((HB(Mezpz)3]MoSC12).’2b These compounds and closely related derivatives provide important benchmark molecules for the development of multiple wavelength X-ray absorption spectroscopy and for the interpretation of X-ray absorption data from enzyme^.^ The facile conversion of the six-coordinate oxomolybdenum(1V) complexes to their sulfido analogues is the first example of such a reaction for a pseudooctahedral mononuclear molybdenum center. Previous conversions have involved nonoctahedral stereochemistries or polynuclear metal center^.^-'^^*^*^^ Finally, we note that the generally broad 95MoN M R signals for oxomolybdenum(1V) compounds and our inability to observe 95MoN M R spectra for the sulfidomolybdenum(1V) compounds offer little encouragement for the direct observation of such centers in enzymes by 95MoN M R . ~

(64) Young, C. G.; Cleland, W. E., Jr.; Enemark, J. H., manuscript in preparation. (65) Hall, M. B.; Fenske, R. F. Inorg. Chem. 1972, I ! , 768.

Acknowledgment. We thank Drs. B. R. James and I. S. Thorburn of the University of British Columbia for recording the 400-MHz ‘H N M R spectra, Dr. K. A. Christensen for assistance with the 95MoN M R spectroscopy, Dr. F. E. Mabbs and Dr. D. Collison for recording the near-IR spectra, and Dr. W. E. Cleland, Jr. for helpful discussions. Support of portions of this work by the U S . Department of Agriculture (Grant 84-CRCR-1-1416) and the National Institutes of Health is gratefully acknowledged. Registry No. la, 99113-26-5; lb, 99127-98-7; IC, 99127-99-8; Id, 107441-39-4;Za, 107441-40-7;2b, 107441-41-8;2b.CH2CI2, 10744144-1; Zc, 107441-42-9;2d, 107441-43-0;c ~ s - M o O ~ ( S ~ C N39248M~~)~, 36-7; cis-Mo02(S2CNEt2)2,18078-69-8;cis-MoO2(S2CNPr2),,1807870-1; cis-Mo02(S2CNBu2),,18078-71-2. Supplementary Material Available: Tables of anisotropic thermal parameters, calculated hydrogen atom positions, and interatom distances and angles for (HB(Me2pz)3JMoO(S2CNEt,) and (HB(Me2pz)3]MoS(SzCNEt2)CH2Cl~ (1 3 pages); structure factor tables for (HB(Me2pz)3}MoO(S,CNEt,) and (HB(Me2pz)3}MoS(S2CNEt2)-CH2Clz (3 1 pages). Ordering information is given on any current masthead page.

Synthesis of N,N’- 1,2-Vinylidene and 1,2-Phenylene Bridged Porphyrins. X-ray Crystal and Molecular Structure of an N,N’-(Diphenyl- 1,2-vinylidene)-meso-tetraphenylporphyrin Henry J. Callot,*t R&myCromer,t Alain Louati,l Bernard Metz,gL and Bernard ChewierL Contributionfrom the Laboratoire de Chimie Organique des Substances Naturelles (U.A. 31) and the Laboratoire d’Electrochimie et de Chimie Physique du Corps Solide (U.A. 405), DZpartement de Chimie. UniversitZ Louis Pasteur, the Laboratoire de Chimie MinPrale (U.A. 405), E.H.I.C.S., and the Laboratoire de Cristallographie Biologique, I.B.M.C. du C.N.R.S..Strasbourg, France. Received October 31, 1986

Abstract: The synthesis of N,N’-1,2-vinylidene and 1,2-phenylene bridged porphyrins, which are models of the inactivation products of cytochrome P-450 in the presence of 1-aminobenzotriazole (ABT) has been accomplished. They are prepared from N-aryl- or N-styrylporphyrins either by oxidation with amine cation radicals or electrochemically. Alternatively the direct reaction of a cobalt(II1) porphyrin with ABT gave an N,N’- 1,2-phenyleneporphyrin and an N-phenylporphyrin. The structure of an N,N’-(diphenyl-1,2-~inylidene)-meso-tetraphenylporphyrin, as its hydroperchlorate, was determined by X-ray crystallography. It showed (i) a considerable folding of the new seven-membered ring formed by the introduction of the 1,2-vinylidenegroup, (ii) that the protonated nitrogen atoms are the unsubstituted ones, and (iii) that the r-electron delocalization in the porphinato core is only moderately affected by the insertion of the two-carbon bridge.

The suicidal inactivation of cytochrome P-450 by l-aminobenzotriazole (ABT) and related compounds’*2is of considerable interest since ABT, by itself of low toxicity, acts as an efficient synergist of insecticides3 and herbicides4 by inhibiting the cytochrome P-450 mediated detoxication pathways. When, in 1981, Ortiz de Montellano and his collaborators’ suggested structure 1 (4 isomers) as the modified porphyrinic component of deactivated cytochrome P-450, it was the first N,N’-phenylene bridged porphyrin, and even the first N-C-C-N when bridged theporphyrin, full account ever of identified the isolation or synthesized. of the naturalOnly product in 1984, was published,2 appeared simultaneously in the literature5 the preparation, by acid-catalyzed enamine formation, of an N,N’vinylideneporphyrin 2. This is in contrast with the series of ‘U.A. 31, Departement de Chimie. *U.A.405, Dtpartement de Chimie. $ U . A .405, E.H.I.C.S. 1I.B.M.C. du C.N.R.S.

0002-7863/87/1509-2946$01.50/0

Scheme I

R 0 1 p =-@-a k

X

e+&

O =

N’

‘N

0

*‘

porphyrin M = Fe,Co

one-carbon-bridged porphyrins which have been synthesized over the last 10 (1) Ortiz de 161-764.

Montellano, P. R.; Mathews, J. M. Biochem. J . 1981, 195,

0 1987 American Chemical Society

J . Am. Chem. SOC.,Vol. 109, No. 10, 1987 2941

N,N'- (Diphenyl- 1,2-~inylidene)-mesotetraphenylporphyrin

1

(1 of 4 Isomers1

2

4

R=H Raalkyl

3 R-Ws

To explain the natural reaction, an intermediate benzyne (under oxidative conditions ABT acts as an efficient benzyne precursor9) was postulated.2 Its addition across an N-Fe bond followed by Fe N' migration would lead to the observed products (Scheme I). The metal-nitrogen migration would be one further example of a now classical reaction of organometalloporphyrinsIbl1 (Scheme I). In the present article12 we will describe several methods for obtaining two-carbon bridged porphyrins, either by forming successively two N-C bonds or by a one step biomimetical bridging reaction. In particular the first synthesis of N,N'-1,2phenyleneporphyrins and the first crystal structure of a N,N'1,2-~inylideneporphyrinwill be presented. While this work was completed, an elegant and conceptually different synthesis of N,N'- 1,2-~inylideneporphyrins3 was published by Setsune and et al.13 starting from a cobalt porphyrin cation radical and an alkyne as a model for a hypothetical benzyne intermediate.

-

Preparative Results and Discussioo Cyclizationof Cobalt(II) N-Styrylporpbyrins. Styrylcobalt(II1) porphyrins 5 and 6 (meso-tetraphenylporphyrin series = TPP) were obtained from halogenocobalt(II1) porphyrins and diazo esters according to known pr0~edures.l~To avoid the loss of cobalt and the deactivation of the porphyrin nucleus on protonation, we 7 and 8, respectively, performed the migration step 5 and 6 by using (p-BrC6H,)3N'+SbC16- ( 9 ) instead of the usual acidic conditions (CF3COOH/air).11b*C It was not necessary to isolate compounds 7 and 8, and, in the presence of an excess oxidant, we directly obtained the SbCl, complexes 10 (20%) and 11 (12%).

-

(2) Ortiz de Montellano, P. R.; Mathews, J. M.; Langry, K. C. Tetruhedron 1984, 40, 511-519. (3) Feyereisen, R.; Langry, K. C.; Ortiz de Montellano, P. R. Insect. Biochem. 1984, 14, 19-26. (4) (a) Gaillardon, P.; Cabanne, F.; Scala, R.; Durst, F. Weed Science 1986, in press. (b) Werck-Reichhart, D. Thesis, UniversitC Louis Pasteur, Strasbourg, 1985. ( 5 ) Setsune, J.; Dolphin, D. Organometallics 1984, 3, 440-443. (6) (a) Johnson, A. W.; Ward, D.; Batten, P.; Hamilton, A. L.; Shelton, G.; Elson, C. M. J. Chem. SOC.,Perkin Trans. 1 1975, 2076-2085. (b) Bartczak, T. J. Acta Crystallogr., Sect. C Cryst. Struct. Commun. 1985, (241, 604-607. (7) Callot, H. J.; Fischer, J.; Weiss, 1272-1 276.

R.J . Am. Chem. SOC.1982, 104,

(8). (a) Lange, M.; Mansuy, D. Tetrahedron Lett. 1981,2561-2564. (b) Chewer, B.; Weiss, R.; Lange, M.; Chottard, J.-C.; Mansuy, D. J. Am. Chem. SOC.1981, 103, 2899-2901. (c) Wisnieff, T. J.; Gold, A.; Evans, S.A,, Jr. J. Am. Chem. SOC.1981, 103, 5616-5618. (9) (a) Campbell, C. D.; Rees, C. W. J . Chem. SOC.C 1969, 742-747. Campbell, C. D.; Rees, C. W. J . Chem. SOC.C 1969, 748-751. (10) Iron series: (a) Ortiz de Montellano, P. R.; Kunze, K. L. J . Am. Chem. SOC.1981, 103, 6534-6536. (b) Ortiz de Montellano, P. R.; Kunze, K. L.; Augusto, 0. J. Am. Chem. SOC.1982,104, 3545-3546. (c) Mansuy, D.; Battioni, J. P.; DuprC, D.; Sartori, E.; Chottard, G. J . Am. Chem. SOC. 1982,104,6159-6161. (d) Kunze, K. L.; Ortiz de Montellano, P. R. J . Am. Chem. Sac. 1983,105, 1380-1381. (e) Lanpn, D.; Cocolios, P.; Guilard, R.; Kadish, K. M. J . Am. Chem. SOC.1984,106,4473-4478. (f') Balch, A. L.; Renner, M. W. J . Am. Chem. Soc. 1986, lQ8, 2603-2608. ( 1 1) Cobalt series: (a) Dolphin, D.; Halko, D. J.; Johnson, E. Inorg. Chem. 1981, 20, 4348-4351. (b) Callot, H. J.; Metz, F. J. Chem. Sac., Chem. Commun. 1982, 947-948. (c) Callot, H. J.; Metz, F.; Cromer, R. Nouu.J. Chim. 1984, 8, 759-763. (d) Callot, H. J.; Cromer, R.; Louati, A,; Gross, M. Nouu.J. Chim. 1984, 8, 765-770. (12) Fragments of this work were published as preliminary reports: (a) Callot, H. J.; Cromer, R. Tetrahedron Lett. 1985, 26, 3357-3360. (b) Callot, H. J.; Cromer, R.; Louati, A.; Gross, M. J. Chem. SOC.,Chem. Commun. 1986, 767-769. (13) Setsune, J.; Ikeda, M.; Kishimoto, Y.; Kitao, T. J. Am. Chem. SOC. 1986, 108, 1309-1311. (14) (a) Callot, H. J.; Schaeffer, E. J . Organomet. Chem. 1978, 145, 91-99. (b) Callot, H. J.; Schaeffer, E. J . Orgunomer. Chem. 1980, 193, 111-115.

The very low polarity of 10 and 11 excluded a saltlike structure as (H-porphyrin)+-Sbcl6-. Analytical data confirmed that a neutral porphyrin-SbC1, was present (another neutral porphyrin-SbCls complex will be described later in this article). In these compounds the porphyrin acts as a neutral monodentate ligand whereas in all known antimony-porphyrin complexes characterized so far the macrocycle acts as a tetradentate ligandI5 (Scheme 11). The SbCl, complexes are rather unstable in solution and were always accompanied by a polar fraction formulated as the corresponding salts 12 (9%) and 13 (26%) which were isolated as perchlorates. The conversion could be quantitatively performed when a CH2C12or toluene solution of 10 or 11 was treated with HC1 or silica gel (this last reaction is slow enough at room temperature to allow the isolation of pure 10 and 11). Salts 12 and 13 were also prepared direclty from 5 and 6 by using the cation radical (p-BrC6H4),N'+C10,- (14). The rather low total yields (10 12: 29% and 11 13: 38%) reflect the low yields in the styrylcobalt cobalt N-styrylporphyrin step. When compound 7 was isolated and treated with 14 it gave 12 in 68% yield. The bridging reaction was extended to the octaethylporphyrin series (OEP), and 15 gave 16 on treatment with excess 14. The visible and N M R spectra of the bridged porphyrins, as SbC1, complexes or as salts, are almost identical suggesting that SbCls and the proton are located on the same N atom(s) and exert a similar effect on the macrocycle. Both the SbC1, complexes and the salts display the expected high field resonances for the bridge protons, e.g., methyl signal at -2.99 ppm for 10 and 12. The bridge ortho phenyl proton resonances at 0.65 ("inside") and 4.35 ppm ("outside") illustrate for 10 and 12 the very large chemical shift differences induced by the relative positions of these protons with respect to the porphyrin a-system. The spectra of 11 and 13 gave two additional informations: (a) The signals of the pyrrole protons (2 AB systems) indicate a plane of symmetry, at least above -50 "C; the SbC1, group or the proton attached to N must exchange rapidly from one N opposite to the bridge to the other. The location of the proton was confirmed by X-ray structure determination (see below) while the structure of the known PdBr2 complex of a one-carbon bridged porphyrin' strongly suggested, by analogy, that SbCls should be attached to the same N atoms. (b) At 25 "C a very broad signal at ca. 2.6 ppm could only be attributed to the ortho protons of the bridge phenyl groups. Variable temperature IH N M R allowed us to determine a 11.5kcal activation barrier corresponding to the restricted rotation of the two phenyl groups (at -20 "C). Two broad signals at ca. 1 and 4.1 ppm were present at -50 O C (in good agreement with the N M R data for 12; insolubility limited the investigations at lower temperatures). Before we were able to obtain monocrystals of a bridged porphyrin and an X-ray structure determination, there remained an alternative between two isomeric structures A (two-carbon bridge) or B (one-carbon bridge). A compound of type B, 17, was described by Mansuy and others,8 and its spectral data were not different enough to convince us that we were handling a different series of bridged macrocycles. However, although both series show the same elements of symmetry, a very useful indication was expected from I3C N M R measurements: depending on the structure, A or B, the vinylidene carbons should give one or two signals. To enhance the bridge carbons signal(s) we prepared 11 by using 13C enriched starting materials (see the details of the synthesis in the Experimental Section). The 13CN M R spectra were run in CDCI, and CD3COCD3at J) 200 MHz under conditions (J modulated spin-echo, delay suitable to observe selectively the quaternary carbons. Only one peak at 124.40 (CDCI,) or 125.0 ppm (CD,COCD3) showed a signal enhancement in the spectrum of the labeled compound. All other resonances corresponding to quaternary carbons were well resolved and clearly identified. This supported the structural assignments which were later confirmed by an X-ray structure determination of compound 13 (see below).

+

-

+

(15) Sayer, P.; Gouterman, M.; Connell, C. R. Acc. Chem. Res. 1982.15, 73-79.

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Callot et al.

We tried to extend the bridging reaction to less substituted substrates like the cobalt complexes of simple N-styryl- or Nvinyl-meso-tetraphenylporphyrins. Compound 18 was already known in the literature1Ic while vinylcobalt(II1) meso-tetraphenylporphyrin 19 was obtained from [Co‘TPPI- and acetylene. Acid-catalyzed rearrangement of 19 gave 20 after metalation. However, treatment of 18, 19, or 20 with 9 never gave a trace of a bridged porphyrin.

‘Ic 6Y,

C6H

C6H5

C6H

C6H5

C6H

phenylporphyrin 30 or its precursor 27 were treated with 9: no bridged compound was observed but instead the slow formation of a product of low polarity which was characterized as 32 (similar results were obtained in the phenyl and 3,4-dimethoxyphenyl series but will not be described here). 32 was independently prepared from the free base 35 and SbCl,. The NMR data for 32 indicate a plane of symmetry: either SbCl, or H is attached to pyrrole C (A being arylated), the remaining group exchanging rapidly, on the N M R time scale, between pyrroles B and D (Scheme IV). A successful cyclization of an aryl group was only achieved after two modifications of the procedure: replacement of 9 by 14 to avoid the “freezing” of the reaction by demetalation followed by SbClscomplexation and application of heat. A first attempt using 31 in refluxing 1,2-dichIoroethane (the methoxy groups were placed to activate the aromatic fragment and end with a symmetrical product) gave 34 (38%; not optimized). Extension to the phenyl series required a prolonged reflux in sym-tetrachloroethane, and 33 was obtained in good yield (66%). Demetalation of the cobalt N-arylporphyrins is a general side reaction. As a result it is rather difficult to separate the bridged porphyrin from the mono-N-substituted base, both being protonated on silica gel. This was overcome by treating the crude mixture with cobalt acetate: only the N-arylporphyrin was metalated, and the less polar complex (= starting material metalated base) could be easily separated from the bridged salt. The same reaction, when applied to the OEP series, failed under chemical conditions (see below for an electrochemical synthesis). Both 33 and 34 show typical N M R spectra for a bridged structure: high field signal for the protons ortho to the pyrrolic N (2.37 and 1.81 ppm, respectively) and an apparent plane of symmetry which reflects a rapid proton exchange between the unsubstituted N atoms. In the case of the N-phenylN,N’-phenylene-meso-tetraphenylporphyrin cyclization we wondered whether cobalt could be replaced by other metals, and accordingly the cyclization conditions were applied to the corresponding CUI’-, Zn”-, Fell-, Ni”-, and Mn“-N-PhTPP’s 36-40 and also to the free base NPhTPP 41, but only in the case of manganese did we isolate 33 albeit in low yield (10%). Compounds 36, 37, and 38 decomposed or demetalated whereas 39 suffered from both loss of metal and phenyl group to end as a mixture of 41 and NiTPP. Base 41 survived the reaction conditions. Electrochemical Experiments. In order to analyze the oxidation step and, hopefully, to optimize the reaction conditions, we replaced cation radicals 9 and 14 by anodic oxidation. The cobalt(I1) N-substituted porphyrins exhibited two monoelectronic oxidation

+

Preparation of N,N’-1,2-Phenyleneporphyrins. Two methods allowed us to obtain bridging phenylene groups from mono-Nsubstituted porphyrins: either an olefinic substrate is oxidatively cyclized to a product which can, in a subsequent step, be aromatized, or an N-arylporphyrin is directly cyclized to the desired structure. The first attemps using the second-and more elegant-method being unsuccessful, we prepared the N-substituted porphyrin 22 (27%) from the known 21,14band oxidized it at low temperature to 23 (at temperatures above 0 “ C extensive decomposition occurred) (Scheme 111). Dehydrogenation of 23 (DDQ) gave N,N’- 1,2-naphthyleneporphyrin24 (56%). Again the high field signals of the aromatic bridge protons confirmed the proximity of the r-system (naphthylene H-3 at 2.18 ppm). Having in hand a method for building an aromatic bridge we chose OEP which is a closer model of the natural products and followed the same reaction sequence. Unfortunately the dehydrogenation of 25 gave a highly insoluble solid which could not be characterized. As said above the first attempts toward the direct cyclization failed. Chlorocobalt(I1) N-(p-methoxypheny1)-meso-tetra-

-

J. Am. Chem.SOC.,Vol. 109, No. 10, 1987 2949

N,N'- (Diphenyl- 1,2-vinylidene)-meso-tetraphenylporphyrin Scheme 111

C6H

9 gH5

C6HS

a

9 C6H

c 6 H 5 @ )

-

6H5

\

C6H5 -C6H5

C6H5

25

Cl0,-

Table I

,q*f 0.01 V0.b

G?,"V/SCE 0.01 v

preparative electrolyses starting 1st 2nd time T yield' (%) material wave wave potentialb ( h ) ("C) 2 25 57 1.58 1.10 7 0.88 1.30 6 120 7 29 0.93 1.54 2 60 32 1.30 31 0.91 1.54 74 120 3 0.85 42 0.80 1.10 "Half-wave potentials (vs. SCE f 0.01 V) on a Pt RDE (1000 rev X min-I) in 1,1,2,2-tetrachIoroethane (1,2-dichloroethane for 7) + nPr4N+C104-(0.05 M). bSame conditions as a but stationary electrode. 'Bridged porphyrins only. f

waves (see Table I). The first wave is diffusion controlled and almost reversible. Analysis of the cyclic voltammetry data (relations between v and Ips, Ipa/I,, Epa)showed that the first oxidation wave was followed by a slow chemical reaction confirming that the electrochemical synthesis of bridged porphyrins was feasible. The half-wave potentials fell within a narrow range (TPP series) and were more positive by ca. 0.25 V than that of the "normal" porphyrin CoTPP. The preparative electrolyses were run at potentials intermediate between the first and the second oxidation waves on the diffusion plateau of the first wave. The supporting electrolyte had to be soluble in the rather nonpolar chlorinated solvents but at the same time had to be hydrophilic enough to be eliminated at the end of the reaction by water washings. We chose n-Pr4N+C10, rather than the more widely used Et4N+C104-(insoluble in chlorinated solvents) or n-Bu4N+C104-(too lipophilic to be extracted). As in the above described chemical reactions heat had to be applied to cyclize the aromatic groups. Two significant differences between the results obtained under chemical and electrochemical conditions were noted: (a) the demetalation of the starting cobalt complexes is amplified during anodic oxidation and severely limits the yields, in particular at high temperatures; (b) whereas an OEP bridged by an aryl group could never be prepared under purely chemical conditions, the use of drastic electrochemical + thermal conditions allowed the isolation of 43 (3%) which is the closest model of the natural product. Half-wave potentials were also measured for compounds 36-38 and 40 (see Table 11) under the same conditions as for the cobalt complexes. Data for 29 (cobalt) and 41 (free base) were added for comparison. The large differences observed for the first wave are not reflected in the E& of the second wave, a parallel behavior being observed for 36, 37, and the free base 41 while large fluctuations of the first wave with regard to the second occurred for 38, 40, and 29.

compd 36 31 38

1st wave 1.25

2nd wave

AEc

1.77

0.52 0.46 1.15

1.59 1.13 1.60 0.45 1.54 0.83 40 0.7 1 1.54 0.61 29 0.93 1.17 0.45 41 0.72 "Same conditions as indicated in Table I. bNickel complex 39 was = E:?, (1st wave) - GT, not studied due to its decomposition. (2nd wave).

Direct Preparation of an N,N'-1,2-Phenylene Porphyrin from ABT and a Cobalt(II1) Porphyrin. We earlier found1lCthat a model reaction of the oxidation of hydrazines by natural systems, like the active Fe-0 form of cytochrome P-450, could be performed: not only cobalt(II1) porphyrins oxidize arylhydrazines but the products-arylcobalt(II1) porphyrins-are analogues of the aryliron(II1) porphyrins, primary products of the inhibition of cytochrome P-450. ABT being a hydrazine derivative we thought that the direct reaction of ABT with a cobalt(II1) porphyrin might produce an N,N'-l,2-phenyleneporphyrin.Indeed, on prolonged heating (>90 OC; no reaction occurred at lower temperatures) and after the usual isolation procedure (see Experimental Section) we obtained two products 33 (1 6%) and 29 (29%) from ClCo'I'TPP and ABT. In addition to 33 and 29 some free base 41 could be detected in the crude reaction mixture, but to facilitate the isolation of the products it was metalated to 29. We checked that 33 and 29 did not interconvert under the reaction conditions (Scheme V). To test Ortiz de Montellano's hypothesis2-the oxidation of ABT gives benzyne which then reacts with the metalloporphyrin-we ran our reaction in the presence of tetraphenylcyclopentadienone, which is known to trap efficiently benzyne as tetraphenylnaphthalene (TPN).9b No TPN could be detected in addition to 33 and 29, but instead several colorless products corresponding to the addition of ABT to the ketone were isolated but not fully characterized. The same side products were found in a blank experiment in the absence of cobalt(II1) porphyrin. Discussion. The bridge formation from cobalt( 11) N-styrylor N-arylporphyrins is obviously a multistep process (Scheme VI, N-phenyl series). The first reaction is a one-electron oxidation (as measured by coulometry) for which three sites are available: cobalt, porphyrin *-system, or the organic group attached to N. This last group, due to the geometry of the molecule, is not conjugated to the porphyrin s-system to which it is almost perpendicular.16 It can be immediately excluded as an oxidation

2950 J . Am. Chem. SOC.,Vol. 109, No. 10, 1987

Callot et al.

Scheme IV

P

w

C6H

C6H

6%

C6H

M X cu ClO, 3_7 Zn CI 3_8 Fe CI 29 Ni ClO, I.,o Mn CI LJ. (free base)

-

35

-e,A

!?z

a0,-

L_3

Cl0,-

Scheme V

Scheme VI

site: one would expect large differences of the Ell2as a function of the substitution (phenyl/dimethoxyphenyl for example). As shown in Table I this was not observed. A choice between the remaining oxidation sites could be made after quantitative electrolysis of 29 little above the first oxidation wave. The ESR signal due to the paramagnetic cobalt(I1) disappeared thus suggesting that the product was a diamagnetic cationic ~obalt(II1)~' species C (electrolysis above the second oxidation wave led to the slow increase of an ESR signal attributed to a *-cation radical). In

a second step an electron transfer'* from an aryl (or a styryl) group to the metal would give an organic cation radical D (N-phenyl series). This step would obviously be facilitated by electron-donating groups or the delocalization of the created charge. The easier transformation of more substituted phenyl or styryl groups confirmed this interpretation. At this stage we earlier proposed12aa nucleophilic attack by a vicinal pyrrolic N, such a process recalling the known anodic oxidative functionalization of aromatics.19 We now favor a C0-C bond formation by radical recombination to form E. Rearomatization by loss of a proton would then give F. Although such a structure (two atoms inserted between the metal and a pyrrolic

(16) This is typical for CIZn(N-Ph)TPP which can be considered as a good model for the corresponding cobalt complexes. See: Kuila, D.; Lavallee, D. K.; Schauer, C. K.; Anderson, 0. P. J . Am. Chem. Soc. 1984,106,448-450. (17) Recently Chang et al. (Salehi, A.; Oertling, W. A,; Babcock, G. T.; Chang, C. K. J . Am. Chem. SOC.1986, 108, 5630-5631) showed evidence, in the OEP series, for an ESR silent cobalt(I1) porphyrin *-cation radical. However in the presence of chloride instead of perchlorate counterion we think that an equilibrium, if any, may be in favor of a metal-centered cation. In addition the absence of bridge formation from the *-cation radicals of the Cu and Zn analogues strongly suggests a direct involvement of the metal in the electron-transfer step.

(1 8) (a) Kochi, J. K. Organometallic Mechanisms and Catalysis; Academic Press: New York, 1978; Chapter 5 . (b) Sheldon, R. A,; Kochi, J. K. Metal Catalyzed Oxidation of Organic Compounds; Academic Press: New York, 1981. (c) Morimoto, T.; Hirano, M.; Echigoya, K.; Sato, T. J . Chem. Soc., Perkin Trans. 2 1986, 1205-1209, and references cited therein. (19) Ross, S. D.; Finkelstein, M.;Rudd, E. J. Anodic Oxidorion;Academic Press: New York, 1975; pp 82-99.

N,N'- (Diphenyl-1,2-vinylidene)- meso- tetraphenylporphyrin

J . Am. Chem. SOC.,Vol. 109, No. 10, 1987 2951

Figure 2. Stereoscopic view of 13.

- 881 Figure 1. An ORTEP drawing of 1 3 showing the atom labeling scheme.

N ) has not yet been characterized, it has been suggested by Ortiz de Montellano2 as a possible intermediate in the course of the natural reaction. One should also remember that compounds in which onezoor three21 atoms are inserted have been synthesized. A reductive elimination from F, similar to that which results in Co N migrations, will give the bridged structure. Loss of cobalt could then be followed, in the presence of 9 and under the mild conditions used for cyclizing the styryl groups, by the formation of the SbC15 complex. The results obtained with metal complexes 3 6 3 8 and 40 can be rationalized if one considers the corresponding redox potentials and oxidation sites. Only in the case of 38 and 40 (Fe, Mn) is a higher oxidation state of the metal easily accessible. However only for 4022is the resulting species a strong enough oxidant to carry out the subsequent electron transfer (E!,2 = 0.71 vs. 0.45 V for 38). For 36 and 37 (Cu, Zn) the oxidation site is the porphyrin a-system, and the electron transfer to the *-cation radical is inefficient enough to allow the omnipresent side reaction, loss of metal, to operate. The reaction which is limited to the nickel complex, cleavage of the phenyl-nitrogen bond, illustrates the great tendency of nickel to prefer a square planar environment. The direct reaction, ABT ClCo'I'TPP, involves first the oxidation of ABT, which is probably coordinated to the metal. In the view of recent findings,23about the behavior of ClCoTPP when it is heated in chlorinated solvents, the oxidizing species could

-

+

(20) (a) Batten, P.; Hamilton, A. L.; Johnson, A. W.; Mahendran, M.; Ward, D.; King, T. J. J . Chem. SOC., Perkin Trans. 1 1977, 1623-1628. (b) Callot, H. J.; Tschamber, T.; Chevrier, B.; Weiss, R. Angew. Chem. 1975,87, 545-546. (c) Chevrier, B.; Weiss, R. J . Am. Chem. Soc. 1976,98,2985-2990. (d) Callot, H. J.; Chevrier, B.; Weiss, R. J . Am. Chem. SOC.1978, 100, 4733-4741. (e) Ichimura, K. Bull. Chem. SOC.Jpn. 1978, 51, 1444-1449. (0 Callot, H. J.; Schaeffer, E. Noun J . Chim. 1980,4, 307-310. (9) Chevrier, B.; Weiss, R.; Lange, M.; Chottard, J.-C.; Mansuy, D. J . Am. Chem. SOC. 1981,103, 2899-2901. (h) Goff, H. M.; Philippi, M. A. Inorg. Nucl. Chem. Letr. 1981, 17, 239-242. (i) Olmstead, M. M.; Cheng, R. J.; Balch, A. L. Inorg. Chem. 1982,21,4143-4148. 0') Balch, A. L.; Chan, Y.-W.; Olmstead, M. M . J . Am. Chem. SOC.1985, 107, 651045514. (21) Battioni, J. P.; Artaud, I.; Duprt, D.; Leduc, P.; Akhrem, I.; Mansuy, D.; Fischer, J.; Weiss, R.; Morgenstern-Badarau, I. J . Am. Chem. SOC.1986, i08,559a-5607. (22) Although the Fe(II)/Fe(III) redox potential is shifted toward more positive values after substitution of a pyrrolic nitrogen, the extent of the shift is not sufficient. For E 1 p measurements on complexes of N-substituted porphyrins see, also: (a) Lavallee, D. K.; Bain, M. J. Inorg. Chem. 1976, 15, 2090-2093. (b) Anderson, 0. B.; Kopelove, A. B.; Lavallee, D. K. Inorg. Chem. 1980,19, 2101-2107. (c) Kuila, D.; Kopelove, A. B.; Lavallee, D. K. Inorg. Chem. 1985, 24, 1443-1446. (23) Kohno, M. Bull. Chem. SOC.Jpn. 1986, 59, 2053-2061, and references cited therein.

Figure 3. The deviations of atoms (8,X lo2) from the mean plane (4N). The orientation is as in Figure 1 ; negative values for atoms which are above the mean plane.

be either cobalt(III), the corresponding a-cation radical, or Cl'. The oxidation will be followed by trapping of the resulting benzyne by the cobalt porphyrin to give intermediate F, which then suffers a reductive elimination to the bridge structure or a protonation to a N-phenylporphyrin (this last possibility may also occur in the N-aryllstyryl cyclization reaction but cannot be evaluated since it will rebuild the carbon skeleton of the starting material). As the reaction proceeds any cobalt(I1) formed can be reoxidized to cobalt(II1) by dioxygen. The fact that no benzyne could be trapped, at least within the limits of detection of TPN, suggests that it reacts as it is formed but also leaves open the possibility of mechanisms not involving benzyne. Crystal Structure of 13. The protonated nonmetallo N,N'(diphenyl- 1,2-~inylidene)porphyrinis shown in Figure 1 with the atomic labeling scheme. The 1,2-vinylidene group bridges two adjacent nitrogen atoms N1 and N2. The single hydrogen atom on a nitrogen of this protonated species is represented by the two observed and supposed half-occupied positions, as was strongly indicated by two-electron density peaks in the vicinity of N3 and N4. They are noted "3 and "4, whereas the remaining hydrogen atoms are noted Hn, Hn being bonded to Cn. The presence of the proton on N3 or N 4 can be confirmed by indirect means, since several bond angles in the porphyrin skeleton have been shown to be very sensitive to imino vs. amino nitrogen at0ms.24925 For example the C,-N-Ca and N-C,-C, angle values lie between the corresponding average values for imino and amino nitrogen atoms.26 Thus the bridge nitrogen atoms are not protonated. Accordingly, Setsune's f o r m ~ l ashould '~ be modified as shown in 3. The four pyrrole nitrogen atoms are approximately coplanar. The plane so defined is noted (4N). As is normally found the four individual pyrrole rings are planar. A table with the characteristics of all mentioned planes is deposited as Supplementary Material.42 The vinylidene bridge forces the substituted pyrrole rings ( N l ) and (N2) to be highly canted from the mean plane (4N), by 22.9 and 20.6O respectively. The two protonated (or better half-time protonated) pyrrole rings (N3) and (N4) are tilted in the direction opposite to that of the N-substituted rings ( N I ) (24) Butcher, R. J.; Jameson, G. B.; Storm, C. B. J . Am. Chem. SOC.1985, 107,29ia-2980. (25) Jameson, G. B.; Ibers, J. A. J. Am. Chem. Soc. 1980,102,2823-2831. (26) The subscripts a,6, m,and p refer to the 01 and 6 carbons of a pyrrole ring, the meso methine carbon atoms, and the phenyl carbon atoms bonded to the core, respectively.

2952 J . Am. Chem. SOC.,Vol. 109, No. 10, 1987

Callot et al.

Table 111. Selected Bond Distances (A) and Bond Angles (deg)"

Nl-CI 1 Nl-CI4 Nl-C9 Cll-c12 c11-C8 C12-C13 C13-Cl4 C14-C5 N2-C21 N2-C24 N2-ClO c21-c22 C21-C5 C22-C23 C23-C24 C24-C6 N3-C31 N3-C34 C31-C32

1.403 (7) 1.418 (7) 1.458 (6) 1.416 (7) 1.403 (9) 1.357 (9) 1.413 (7) 1.397 (8) 1.407 (7) 1.396 (5) 1.451 (6) 1.413 (7) 1.396 (6) 1.362 (7) 1.420 (8) 1.392 (7) 1.378 (7) 1.355 (8) 1.439 (7)

C31-C6 C32-C33 c33-c34 c34-c7 N4-C4 1 N4-C44 C4 1-C42 C41-C7 C42-C43 c43-c44 C44-C8 C5-C51 C51-C52 C51-C56 C52-C53 c53-c54 c54-c5 5 C55-C56

(a) Bond 1.405 (9) 1.335 (9) 1.432 (7) 1.407 (8) 1.376 (7) 1.377 (6) 1.432 (8) 1.392 (6) 1.346 (7) 1.433 (9) 1.398 (7) 1.485 (8) 1.402 (8) 1.377 (9) 1.388 (9) 1.372 (10) 1.364 (8) 1.384 (9)

Distances C6-C61 C61-C62 C6 1-C66 C62-C63 C63-C64 C64-C65 C65-C66 c7-c7 1 C71-C72 C71-C76 C72-C73 c73-c74 c74-c75 C75-C76 C8-C8 1 C81-C82 C8 1-C86 C82-C83

1.494 (7) 1.384 (7) 1.371 (9) 1.388 (8) 1.372 (11) 1.358 (9) 1.391 (8) 1.492 (8) 1.378 (8) 1.387 (10) 1.368 (10) 1.342 (12) 1.358 (11) 1.388 (11) 1.503 (7) 1.392 (9) 1.391 (7) 1.394 (8)

C83-C84 C84-C85 C85-C86 C9-C91 C9-C 10 C91-C92 C91-C96 C92-C93 c93-c94 c94-c95 C95-C96 c 10-c 101 c101-c102 C1 01-C106 C102-C103 C103-C104 C 104-C 105 ClO5-C 106

1.367 (9) 1.373 (11) 1.384 (8) 1.488 (6) 1.333 (6) 1.398 (7) 1.381 (8) 1.389 (7) 1.351 (9) 1.391 (8) 1.383 (6) 1.495 (7) 1.385 (9) 1.384 (8) 1.381 (8) 1.374 (10) 1.378 (1 1) 1.390 (8)

(b) Bond Angles

Cll-Nl-Cl4 C1 l-Nl-C9 C14-Nl-C9 Nl-Cll-C12 Nl-ClI-CS C12-Cll-C8 Cl l-c12-c 13 c 1 2 - c 13-c14 N 1-C 14-C 13 N 1-C 14-C5 c 13-c 14-c5 C2 1-N2-C24 C2 1-N2-C 10 C24-N2-C10 N 2 4 2 1-C22 N2-C21-C22 c 2 2 - c 2 1- c 5 c 2 1-c22-c23 c22-c23-c24 N2-C24-C23 N 2-C24-C6 C23-C24-C6 C3 1-N3-C34 N3-C31-C32 N3-C3 1-C6 C32-C3 1-C6 c31-c32-c33 c 3 2-c3 3-c 34 N3-C34-C33 N3-C34-C7 c33-c34-c7 C41-N4-C44 N4-C41-C42 N4-C4 1-C7 c42-c41-c7 c41-c42-c43

107.3 (4) 122.0 (4) 118.2 (5) 107.6 (5) 127.7 (4) 124.7 (5) 108.9 (5) 108.9 ( 5 ) 107.3 (5) 125.3 (4) 127.0 (5) 107.7 (4) 118.1 (3) 123.9 (4) 107.7 (4) 125.8 (5) 125.8 (5) 108.3 (5) 108.8 (4) 107.5 (4) 127.7 ( 5 ) 124.8 (4) 107.9 (4) 107.0 (5) 128.1 (4) 124.8 (5) 108.9 (5) 106.6 (5) 109.5 (5) 124.9 (4) 125.4 (5) 106.8 (4) 109.3 (4) 124.0 (5) 126.5 (5) 107.2 (5)

c42-c43-c44 N4-C44-C43 N4-C44-C8 C43-C44-C8 c14-c5-c21 c14-c5-c5 1 c21-c5-c5 1 c 5 - c 5 1-c52 C5-C51-C56 C52-C51-C56 c51-c52-c53 c52-c53-c54 c53-c54-c55 C54-C55-C56 C5 1-C56-C55 C24-C6-C3 1 C24-C6-C6 1 C3 1-C6-C61 C6-C61-C62 C6-C61-C66 C62-C6 1-C66 C61-C62-C63 C62-C63-C64 C63-C64-C65 C64-C65-C66 C6 1-C66-C65 c34-c7-c41 c34-c7-c71 c 4 1-c7-c7 1 c7-c71-c72 C7-C71-C76 C72-C71-C76 c71-c72-c73 c72-c73-c74 c73-c74-c75

107.9 ( 5 ) 108.8 (4) 126.1 ( 5 ) 125.0 (4) 122.4 (5) 118.4 (4) 118.6 (5) 119.5 ( 5 ) 121.2 ( 5 ) 119.3 ( 5 ) 120.2 (6) 119.3 (6) 120.7 (6) 120.8 (6) 119.7 (5) 128.2 (4) 116.7 (5) 115.0 (4) 120.9 (6) 120.4 (4) 118.6 ( 5 ) 120.6 (6) 119.9 (5) 119.9 (6) 120.4 (7) 120.6 (5) 123.8 (5) 118.3 (4) 117.8 (5) 121.3 (6) 120.7 (5) 118.0 (6) 121.6 (7) 119.4 (7) 121.3 (7)

C74-C75-C76 C7 1-C76-C75 C 1 1-C8-C44 Cll-C8-C81 C44-C8-C8 1 C8-C81-C82 C8-C81-C86 C82-C81-C86 C8 1-C82-C83 C82-C83-C84 C83-C84-C85 C84-C8 5-C86 C8 1-C86-C85 N 1-C9-C9 1 Nl-C9-C10 c 9 1-c9-c 10 c9-c91-c92 C9-C91-C96 C92-C91-C96 c 9 1-c92-c93 c92-c93-c94 c93-c94-c95 C94-C95-C96 C9 1-C96-C95 N2-ClO-C9 N2-C 10-C 10 1 c9-c10-c101 C l 0-CI 01-c102 C1 0-C1 01-C106 C102-C101-C 106 c101-c102-c103 c102-c103-c104 c 103-c 104-c 105 C 1 0 4 4 105-C 106 ClOl-Cl06-ClO5

119.9 (8) 119.6 (7) 128.2 ( 5 ) 115.7 (4) 116.2 (5) 121.5 (4) 119.8 ( 5 ) 118.7 (5) 121.0 ( 5 ) 119.3 (7) 120.5 (6) 120.9 (5) 119.7 (6) 113.3 (4) 119.9 (4) 125.5 (4) 116.7 ( 5 ) 123.8 (4) 119.4 (4) 120.0 ( 5 ) 120.3 (5) 120.2 ( 5 ) 120.4 (6) 119.7 (5) 120.5 (4) 113.7 (4) 124.4 (4) 117.5 (5) 122.8 (5) 119.7 (5) 119.6 (6) 120.9 (7) 119.8 (6) 119.9 (6) 120.1 (6)

"Numbers in parentheses are esd's in the least significant digits. and (N2), by 10.6' and 19.9', respectively. A side-on view of the protonated base indicating the relative orientations of the pyrrole rings is given in Figure 2. It resembles a crab or a flying saucer possessing a C, pseudosymmetry. This is confirmed by the values of the deviations from the (4N) plane given in Figure 3. The values of the bond lengths in the macrocyclic skeleton are due to its conformation and to the hybridization at the nitrogen atoms. The observed values are consistent with those of equivalent bonds in N-substituted, N,N'-bridged, and protonated porphyrins ~ . ~ * *111). ~~-~~ or r n e t a l l o p o r p h y r i n ~ ~ ~ ~ ~ J(Table (27) McLaughlin, G. M.J . Chem. Soc., Perkin Trans. 2 1974, 136-140. (28) Abeysekera, A. M.; Grigg, R.; Trocha-Grimshaw, J.; Henrick, K. Tetrahedron 1980, 36, 1857-1868. ( 2 9 ) Hirayama, N.; Takenaka, A,; Sasada, Y.; Watanabe, E.; Ogoshi, H.; Yoshida, 2.Bull. Chem. Soc. Jpn. 1981, 54, 998-1004.

The averaged values of the following bond angles in the porphyrin skeleton also are similar to those found elsewhere: C,N-C, = 107.4 (4), N-C,-C, = 108.1 ( S ) , C,-CB-C, = 108.2 (S), N-C,-C, = 126.2 ( S ) , CB-C,-C, = 125.5 (S), C,-C,-C, = 117.1 (5)0.31 The presence of both the bridge and the proton angles. For these angles, influences the values of the C,-C,-C, values between 125 and 127' are normally found.31 The observed values of 122.4 ( 5 ) , 128.2 (4), 123.8 ( 5 ) and 128.2 (5)' are outside angles increases the the interval. The opening of two C,-C,-C, distances HN3-Cl0, H N 4 4 9 , HN3-Hl06, and HN4-sH96. The closing of C14-C5-C21 is due to the bridge, whereas the angle (30) Hrung, C. P.; Tsutsui, M.; Cullen, D. L.; Meyer, E. F.,Jr.; Morimoto, C. N. J. Am. Chem. Soe. 1978, 100, 6068-6076 and references therein. (31) Hoard, J. L. In Porphyrins and Metalloporphyrins; Smith, K . M., Ed.; Elsevier: Amsterdam, 1975; p 337.

J. Am. Chem.Soc., Vol.109, No. 10, 1987 2953

N,N'- (Diphenyl1,2-vinylidene)-meso-tetraphenylporphyrin C34-C7-C41 of 123.8 (5)' compares with a normal one. Consequently, the distances between two adjacent nitrogen atoms, Nl.-N2, N2-N3, N3-N4, and N4-N1, are equal to 2.797 ( 5 ) , 3.131 (7), 2.776 (6), and 3.114 (6) A, respectively. The presence of a vinylidene bridge between two pyrrolic nitrogen atoms has only a slight effect on the a-electron delocalization in the porphinato core. The vinylidene bridge between N1 and N 2 completes a new seven-membered ring in the structure. This ring is highly folded along the line passing through N1 and N2 (see Figure 1). Indeed, the dihedral angle between mean plane (B) containing N1, C9, C10, and N2 and mean plane (C) containing N1, C14, C5, C21, and N2 is equal to 5 3 9 . This folding, in addition to the opening of angles C24-C6-C3 1 and C 4 4 4 8 - C l l mentioned above, avoids strong interactions between HN3 and C10 and between "4 and C9. The observed distances H N 3 - C l 0 and HN4-C9 are equal to 2.41 and 2.40 A, respectively. Steric effects are observed in the bridging group: plane (B), the plane of the bridge, does not contain all the atoms of the olefinic double bond. The atoms C91 and ClOl are 0.34 (1) and 0.25 (1) A out of plane (B). The mean plane (D) containing C9, C10, C91, and ClOl forms a dihedral angle of 14.O0 with plane (B). Thus interactions H96-N4 (2.75 A), H106-N3 (2.76 A), HN3-Hl06 (2.93 A), and HN4-H96 (2.82 A) are reduced. The two phenyl rings attached to the vinylidene bridge are tilted; the values of angles C9-C9 1-C92, C9-C9 1-C96, C1 0 4 1 01-C 102, and C10-C 101-C 106 respectivelyequal to 116.7 ( S ) , 123.8 (4), 117.5 (5) and 122.8 (5)' best indicate this tilting. All these deformations illustrate the crowding around the bridge, both from the porphyrin nucleus and the lateral phenyl groups. No intermolecular interactions of any chemical significance were found to exist in the lattice. Experimental Section General Procedures. Nuclear magnetic resonance spectra were recorded in CDCI,, unless specified, by using Perkin-Elmer R24 and Bruker WP-200 SY (respectively 60- and 200-MHz) spectrometers, and chemical shifts are reported in 6 values (ppm from Me4Si). Coupling constants of pyrrolic and aromatic protons are in the normal ca. 5- or 8-Hz range, respectively, and will not be specified. Visible spectra were taken in CH2CI2 on Hewlett-Packard 845 1A and Varian 2200 spectrometers. Elemental analyses were performed by the Service de Microanalyse de I'Institut de Chimie, Strasbourg. Chromatographic separations were performed by using Merck 60 (70-230 or 230-400 mesh) silica gel columns. Most reactions were followed by using Merck F-250 silica gel TLC plates. Caution: Organic perchlorate derivaiives may detonate upon scraping or heating. The preparation of compounds 5,'" 14:, 18,i4b 22,i4b 26,IIc 27,lIc 29,IIc 30,IIc 37,lIc and 42lIc was described in the literature. Cation radical 9 was purchased from Aldrich. We thank Dr J.-P. Battioni for a generous gift of compound 17. Synthesis of 6. Reaction of deoxybenzoin tosylhydrazone and CICoTPP according to the literature"c gave 6 (74%): IH N M R 6 -1.7 (s, 1 H, vinyl H ) , 2.92 (t, 2 H), 4.67 (d, 2 H), 5.99 (m, 2 H), 6.25 (m, 3 H), 6.61 (m, 1 H ) (side chain 2 C6H5),7.5-8.1 (m, 20 H, meso C6H5),8.81 (s, 8 H, pyrrolic H); visible A,, 414 nm ( 6 136000), 530 (13500). Anal. ( C S ~ H ~ ~ N ~CC, O H,) N. , Bridged Porphyrins from 5 and 6. A solution of 5 (75 mg, 0.095 mmol) and 9 (150 mg, 0.184 mmol) in CH,CI2 (60 mL) was stirred at 25 OC for 25 min, concentrated to 10 mL, and poured on top of a silica gel column (50 g in CH2C1,). Elution with CH2CI2-ethyl acetate (95:5) gave 10 (20 mg, 20%; crystallized from CH2C12-hexane), while CH,CI,-CH,OH (95:5) eluted 12. The fraction containing 12 was evaporated, and the residue was dissolved in CH,OH. Addition of aqueous NaC104 precipitated a solid which was washed (H,O), dried under vacuum, and crystallized from CH,C12-hexane (7 mg, 9%). An identical procedure starting from 6 gave 11 and 13 (respectively 12 and 26%). The relative yields vary considerably, depending on the duration of the separation and by consequence on the transformation of the SbC15complex on silica gel. SbCIJ Complex 10 and Salt 12: ' H N M R 6 -2.89 (s, 3 H, CH,), ca. -2.7 (br signal, 1 H, N H , 12 only), 0.65 (d, 1 H ) , 4.31 (d, 1 H), 5.46 (t, I H), 6.40 (t, 1 H), 6.59 (4 1 H ) (bridge C6H5), 7.8-8.5 (m, 20 H, mew C&), 8.54, 8.74, 8.93, and 8.96 (4d, 4 H , pyrrolic H), 9.05-9.15 (m, 4 H, pyrrolic H); visible A,, 428 nm (t 147000), 554 (9 500). 592

(32) Bell, F. A,; Ledwith, A,; Sherrington, D. C. J . Chem. SOC.C 1969, 2719-2720.

(14000), 642 (6500). Anal. 10 (C53H,6N4C15Sb)C, H , N . Anal. 12 (C53H37N4C104 + H2O) C, H, N. SbC15 Complex 11 and Salt 13: IH NMR (at room temperature) 6 ca. -2.5 (br signal, 1 H, NH, 13 only), 2.6 (br signal, 4 H, bridge C6H5 o-H), 5.94 (br t, 4 H , bridge C6H5m-H), 6.36 (t, 2 H, bridge C6H5p-H), 7.0-8.4 (m, 20 H, meso C6H5), 8.78 and 8.83 (AB, 4 H, pyrrolic H), 9.17 and 9.22 (AB, 4 H, pyrrolic H); visible A,, 428 nm (t 160000), 554 (IOOOO), 592 (14700), 640 (6200). Anal. 11 (C5aH38N4C15Sb+ CH2C12,NMR detected) C, H, N. Anal. 13 (C5aH,9N4CI04 + CH2C12, N M R detected) C, H, N . The variable temperature 'HN M R measurements were performed between -50 O C and +50 O C by using salt 13 in CDC13 solution. The activation barrier was evaluated by using either the ortho or meta signals of the bridge phenyl groups (coalescence at ca. -20 and -30 'C; AG*, calculated by using Eyring formula, 11.5 and 11.1 & 0.2 kcal mol-'. At -50 O C ortho and meta protons appeared at 1 and 4.1 (ortho) and 5.5 and 6.4 ppm (meta). The conversion of the SbCI, complexes 10 and 11 into salts 12 and 13 could be accomplished as follows: (a) addition of silica gel to a solution of 10 (respectively l l ) , evaporation of the solvent, heating at ca. 100 OC for a few minutes (the reaction takes 1-3 h at 25 "C), elution with CH2C12CH30H;(b) addition of p-toluenesulfonic acid to a toluene solution or of 1 N HCI to a toluene-CH,OH solution; (c) heating in refluxing toluene for a few hours. Alternatively salts 12 and 13 are accessible from 5 and 6 by using cation radical 14 (yields similar to the total yields given above). Cobalt Complex 7. It was prepared in quantitative yeild from corresponding basell' which was treated with Co(OAc), in boiling CH,Cl2CH,OH. Evaporation of C H Q , followed by precipitation of the product with aqueous NaCl gave 7 which was washed (H,O), dried under vacuum,crystallized from CH2CI2-hexane, and used as such. Salt 12 from 7. A solution of 7 (152 mg, 0.185 mmol) and 9 (300 mg, 0.37 mmol) in CH2CIz (40 mL) was stirred at 25 O C for 20 min. The solution was concentrated to I O mL and poured on top of a silica gel column (75 g in CH,CI,). The column was kept at room temperature for 3 h to complete the decomplexation of SbC15. Elution (CH2C12CH,OH, 95:5) gave a reddish green fraction which was purified as described above to give salt 12 (105 mg, 68%). Preparation of Bridged Octaethylporphyrin 16. A mixture of CICoOEP (272 mg, 0.43 mmol), deoxybenzoin tosylhydrazone (500 mg, 1.37 mmol), NaOH (600 mg), diglyme (10 mL), and water (1 mL) was stirred and heated at 90 OC for 2 h. After cooling, it was partitioned between toluene and water; the toluene phase was thoroughly washed (HzO), dried (NazS04),and evaporated. Crystallization of the residue from CH2C12-CH30H gave 15 (263 mg, 79%; one spot on TLC) used as such. A solution of 15 (120 mg, 0.16 mmol) and 9 (240 mg, 0.3 mmol) in CH2C12 (50 mL) was kept at room temperature for 3 h. The workup followed the procedure used to isolate 12 and gave 16 (27 mg; 21%): ' H N M R 6 ca. -3.5 (br signal, 1 H, N H ) , 1.54, 1.62, 1.89 and 2.01 (4t, 24 H, CH3), 2.3 (br s, 4 H, C6H5o-H), 3.8-4.6 (m, 16 H, CH,), 5.69 (t, 4 H, C&5 m-H), 6.11 (t, 2 H, C6Hs p-H), 10.28, 10.51, and 11.22 (3s, 2 + 1 + 1 H, meso H); visible A, 404 nm ( t 80000), 538 (7700), 572 (9600), 616 (4300). Anal. (C50H5SN4CI04 O.SCH,CI,, N M R detected) C, H, N. Preparation of WLabeled 11. Benzoic acid, ca. 10% labeled on carboxy group, was prepared" from C6H5MgBr and "CO, (from Ba"C0, and H2SO4). Reduction34(LiAIH,) and partial r e ~ x i d a t i o n ~ ~ (K2Cr207,HzS04, phase transfer) gave C6H5"CHO. Cyanide-catalyzed c o n d e n ~ a t i o ngave ~ ~ benzoin which was reduced" to deoxybenzoin and condensed with tosylhydrazine in CH,OH. The next steps to 11 are described above. The I3C NMR spectrum (J modulated spin-echo, delay ' / 2 J) showed only the quaternary carbons. For unlabeled 11: (CDCI,) 6 124.40 (bridge), 124.52 (bridge C6H5), 126.19, 127.17, and 127.74 (meso), 136.69, 138.75, and 141.18 (meso C6H5),148.52, 148.85, 149.48, and 151.17 (pyrrolic C); (acetone) 6 125.00 (bridge), 125.45 (bridge e&), 127.10, 127.40, and 128.40 (meso), 137.65, 139.65, and 142.15 (meso C6H5), 149.23, 149.63, 150.13, and 151.93 (pyrrolic C). Labeled 11: only the sharp singles at 124.40 (CDCI,) and 125.00 (acetone) showed the expected signal enhancement. Vinylcobalt(II1) meso-Tetrapbenylporphyrin(19). We followed the procedure" used for the preparation of vinylcobalt(II1) octaethyl-

+

(33) Lintermans, J.; Benakis, A,; Ratonis, R. J . Labelled Compd. 1970, 6, 289-297.

(34) Nystrom, R. F.; Brown, W. G. J . Am. Chem. SOC.1947, 69, 2548-2549. (35) Pletcher, D.; Tait, S. J. D. Tetrahedron Lett. 1978, 18, 1601-1602. (36) Adams, R.; Marvel, C. S. Organic Syntheses; Wiley: New York, 1941; Collect. Vol. I, pp 94-95. (37) Carter, P. H.; Craig, J. C . ;Lack, R. E.; Moyle, M. Org. Synrh. 1960, 40. 16-18.

2954 J . Am. Chem. SOC.,Vol. 109, No. 10, 1987 Table IV. Crystallographic Data formula fw space group

A c, A

Pi

12.343 (1) 14.172 (2) 16.150 (2) 103.96 (1) a,deg 110.71 (1) P, deg 86.76 (1) 7 , deg v. A3 2563 (2) 1 1.34 1.33 (1)' 23.1 'Flotation in an aqueous potassium tartrate solution. a,

b, A

Callot et al.

scan type scan width, deg data collctn range no. of unique data no. of data, I > 3 4 0

esd largest peak, e A-' (final difference Fourier map)

w/20 0.70 0.14tgO 2 < 0 < 62" 8066 4217 0.08 618 0.067 0.087 1.484 0.49

largest shift/esd (final least-squares cycle)

0.13

P

no. of refined variables

porphyrin but started from [CoTPPI- and acetylene (yield 32%): IH N M R 6 -1.39, -0.40, and -0.1 1 (3 dd, 3 H, J = 12,4.7, and 3 Hz, vinyl), 7.7-8.1 (m, C&), 8.83 (s, 8 H, pyrrolic H); visible A,, 414 nm (e 124000), 528 (14200). Anal. (C46H31N4Co)C, H , N . Cobalt Complex of N-Vinyl-meso-tetraphenylporphyrin20. Vinylcobalt(II1) meso-tetraphenylporphyrin 19 (100 mg, 0.13 mmol) in CH2CI2 (50 mL) was treated with CF,COOH (3 mL). After 5 min at room temperature the solution was neutralized (aqueous NH,), washed (H,O), dried (Na2S04),and concentrated to a small volume. Chromatography (Merck standardized alumina, 20 g in CH2CI2) gave a green fraction which was evaporated. The base crystallized from CH2C12C H 3 0 H (+5% triethylamine) (47 mg, 51%): ' H N M R 6 -1.64, 1.09, and 1.20 (dd + 2 d, 3 H, J = 15, 8, and 0 Hz, vinyl), 7.74 (s, 2 H, pyrrolic H), 7.8-8.3 (m, 20 H, C6H,), 8.45 and 8.61 (AB, 4 H , pyrrolic H), 8.82 (s, 2 H, pyrrolic H). Treatment of this base with Co(OAc), (see preparation of 7) gave 20 (83%). Visible A, 450 nm (e 128 000), 568 (7 900), 618 (10 700), 666 (6 300). Anal. (C46H31H4CICo)C, H, N. Oxidation of 18, 19, and 20. When treated with excess 9 (same conditions as for 5 and 6) 18,19,or 20 gave several products but none could be identified as a bridged porphyrin. N-Substituted Complex 22. Porphyrin 211" (500 mg, 0.59 mmol) was dissolved in CH2CI2(30 mL) and cooled to -5 "C. After addition of 9 (1 g, 1.2 mmol) the solution was kept at -5 "C for 5 min, concentrated, and chromatographed (silica gel 230-400 mesh; 75 g in CH2C12). Elution with CHCI3-CH3OH (98:2) gave a green fraction which was evaporated. The residue was dissolved in CH,OH. Addition of aqueous NaCl precipitated 22 which was recrystallized from CH2CI2-hexane (142 mg, 27%). Visible A,, 450 nm (e 113000), 570 (6000), 630 (9000), 680 (10000). Anal. (C54H36N4CICO + H 2 0 ) C, H, N . Dihydronaphthylene Bridged Porphyrin 23. To a solution of cobalt complex 22 (46 mg, 0.054 mmol) in CH2C12(6 mL) cooled to -5 "C was added 14 (76 mg, 0.124 mmol). The solution was stirred for 3 h during which the temperature raised to +5 OC. Concentration of the solution followed by workup as above for 22 (NaCI replaced by NaC104) gave 23 (22 mg, 48%): IH N M R 6 -3.80, -3.22, -1.53, and -0.45 (td, dd, td, dd, 4 H , J = 13 and 5 Hz, CH2-CH2), 4.51, 5.28, 6.22, and 6.45 (d, d, t, t, 4 H, aromatic fragment of the bridge), 7.9-8.2 (m, 20 H, meso C6H,), 8.68-9.13 (m, 8 H, pyrrolic H); visible A, 434 nm (e 64 loo), 558 (6 600), 594 (8 000),648 (5 900). Anal. (C54H31N4C104 + CH2C12) H, N , C calcd for 71.30, found 70.55. Naphthylene Bridged Porphyrin 24. A solution of 23 (20 mg, 0.025 mmol) and dichlorodicyanoquinone (60 mg, 0.26 mmol) in chlorobenzene was refluxed under argon for 24 h. Chromatography over silica gel (50 g, eluent CHCI3-CH30H, 97:3) successively gave a little starting material followed by a fraction containing 24 (10 mg, 50%, after usual workup): 'H N M R 6 2.18, 4.87, 5.50, 6.12, 6.53, and 6.79 (d, d, d, d, t, t, 6 H, naphthylene bridge), 7.6-8.5 (m,20 H, meso C6H5),8.8-9.2 (m, 8 H, pyrrolic H); visible A, 436 nm (e 98 700), 562 (7 300). 600 (10300), 650 (6500). Although the fit between spectral data and structure was excellent, and although the purity, as appreciated by TLC, seemed to be high, we did not obtain acceptable analytical results for 24. Bridged Octaethylporphyrin 25. A mixture of tetralone tosylhydrazone (1.2 g, 3.8 mmol), NaOH (1 g), H 2 0 (1 mL), and diglyme (10 mL) was stirred and warmed at 90 "C for 1 h. After cooling, it was diluted with H 2 0 (100 mL) and extracted with pentane (2 X 20 mL). This pentane solution of diazotetraline was washed (2 X 60 mL of H 2 0 ) , dried (Na2S04),and added at once to a stirred solution of ClCoOEP (700 mg, (38) Ogoshi, H.; Watanabe, E.; Koketsu, N.;Yoshida, Z. Bull. Chem. SOC. Jpn. 1976,49, 2529-2536.

+

1.2 mmol) in CH2C12(70 mL). After 1 min the solvent was evaporated, and the residue dissolved in toluene was filtered through an alumina column (200 g in toluene). This solvent eluted a red product (290 mg, ca. 36%) which was immediately dissolved in CH2C12(25 mL), cooled (-5 "C), and oxidized with 9 (780 mg, 0.95 mmol). After 10 min the solution was poured on a silica gel column (200 g in CH2C12),left for 12 h, and then eluted with CH2CI2-CH3OH (99:l). Evaporation of CH2CI2and precipitation from CH,OH with aqueous NaC104 gave 25 which was crystallized from CH2CI2-hexane (30 mg, 10%): 'H N M R 6 -4.00, -3.66, -2.02, and -0.69 (td, dd, td, dd, 4 H , J = 16 and 5 Hz, CH2-CH2) 1.5-2.0 (m, 24 H, CH,), 3.95-4.4 (m,17 H , ethyl C H 2 1 Ar H), 5.13, 6.05, and 6.20 (d, t, t, 3 H, Ar H), 10.19, 10.56, 10.77, and 10.98 (4 s, 4 H, meso H); visible ,A, 404 nm (e 96 200), 538 (6 800), 572 (9 SOO), 616 (2300). Anal. (C4,H5,N,CI04) C, H, N. When compound 25 and DDQ were heated in refluxing chlorobenzene no more starting material was present after 1 h while simultaneously a solid separated. The absolute insolubility of this material precluded any characterization. 3,4-Dimethoxyphenylcobalt(III) meso-Tetraphenylporphyrin (28). l-Bromo-3,4-dimethoxybenzene(1.8 g, 8.5 mmol) in diethyl ether (20 mL) was treated, at -80 "C and under argon, with n-BuLi (8.5 mmol) in hexane (5 mL). The resulting solution was slowly (2 h) warmed to 20 "C and then added to a suspension of ClCoTPP (640 mg,0.9 mmol) in toluene-diethyl ether 70:30 (80 mL). After 5 min the excess reagent was decomposed by addition of CH,OH (3 mL), and the solution was concentrated. Addition of C H 3 0 H gave 28 (634 mg, 87%): 'H N M R b -0.45 and -0.14 (d + dd, 2 H , J = 2 and 8 Hz, (CH30)2C6H3ortho H), 2.49 and 2.91 (2 s, 6 H, CH,O), 4.35 (d, 1 H, (CH30)2C6H,meta H), 7.6-8.2 (m,20 H, meso C6H5),8.65 (s, 8 H, pyrrolic H); visible ,A, 410 nm (e 142000), 528 (16800). Anal. ( C 5 2 H 3 7 N 4 0 2 CC, ~ ) H, N calcd 6.93, found 6.19. The acid-catalyzed rearrangementllCof 28 followed by metalation of the base (see above) gave N-substituted cobalt(I1) complex 31 (80%) which was used as such for the cyclization: visible A, 444 nm (e 84000), 582 (600), 632 (9300), 688 (5 100). Attempted Cyclization 27 9. To a solution of 27 (77 mg, 0.099 mmol) in CH2CI2 (100 mL) was added 9 (1 50 mg, 0.1 84 mmol). The solution turned immediately green (formation of mono-N-substituted porphyrin) and was kept at 20 OC for a week during which a green product of low polarity formed at the expense of the polar one. Concentration of the solution and chromatography (silica gel, 40 g in CH2CI2)gave 32 (eluted with CH2CI2-AcOEt, 95:5) which was crystallized from CH2C12-hexane (56 mg,55%): 'H N M R b -2.9 (br s, 1 H , NH), 2.15 (d, 2 H , N-aryl ortho H), 2.70 (s, 3 H, OCH,), 4.48 (d, 2 H, N-aryl meta H), 7.7-8.5 (m, 20 H, meso C6H5), 8.22 (s, 2 H, pyrrolic H), 8.74 (s, 2 H , pyrrolic H), 8.83 and 8.85 (AB, 4 H, pyrrolic H); visible A, 443 nm (e 181 000), 602 (9 loo), 664 (18 000). Anal. ( C ~ ~ H ~ ~ N ~ CC, I SH, ON S .~ ) Compound 38 was obtained independently from N-anisyl-mesotetraphenylporphyrin1Ic(20 mg, 0.028 mmol) and excess SbCl5 (0.5 mL) in CH2C12(10 mL). Filtration of the solution over silica gel (10 g, eluent CH2CI,-AcOEt, 95:5) gave 32 (16 mg,56%) found to be identical with the product from 27 (TLC, IH N M R , visible). Bridged Porphyrin 33. A solution of 29 (643 mg, 0.76 mmol) and 14 (1.5 g, 2.4 mmol) in 1,1,2,2-tetrachloroethane(55 mL) was heated under reflux for 70 h. After having been cooled to 60 "C, Co(OAc)2 (10 equiv/porphyrin, in a minimal amount of warm CH,OH) was added to metalate the free base 40 formed during the reaction (this complexation takes less than 5 min). The crude mixture was cooled to 25 OC and absorbed on silica gel (ca. 300 g in CH2CI2). Elution with CH2C12C H 3 0 H (98:2) gave the starting material (14%; including the metalated base) which was precipitated from CH,OH with aqueous NaCl (or

+

+

N,N’- (Diphenyl- I ,2-vinylidene) - meso- tetraphenylporphyrin aqueous NaC104 to produce the corresponding perchlorate). CHZCI2C H 3 0 H (95:5) eluted the bridged porphyrin 33 which was precipitated from C H 3 0 H with aqueous NaC104, washed (HZO), and crystallized from CH,C12-hexane (394 mg, 66%): ‘H N M R 6 ca. -3.7 (br signal, 1 H, NH), 2.37 and 4.5 1 (AA’XX’, 2 H 2 H, phenylene), 7.8-8.3 (m, 20 H, meso C,H,), 8.85 and 8.93 (AB, 4 H, pyrrolic H), 9.01 and 9.09 (AB, 4 H, pyrrolic H); visible ,A, 442 nm (c 93 000), 566 (7 800), 602 (12000), 656 (6300). Anal. (C50H,,N4C104 + H20) C, H , N . The same procedure, when applied to the corresponding starting material in the OEP series, did not yield any bridged porphyrin. Bridged Porphyrin 34. A solution of 31 (50 mg, 0.055 mmol) and 14 (1 00 mg, 0.16 mmol) in 1,2-dichloroethane ( I 2 mL, filtered through a bed of alumina) was heated under reflux for 36 h. Workup as for 33 gave 34 (18 mg, 38%): IH N M R d ca. -3.6 (br signal, 1 H, NH), 1.81 (s, 2 H, phenylene), 2.25 (s, 6 H, OCH,), 7.8-8.25 (m, 20 H, meso C&), 8.85 and 8.93 (AB, 4 H, pyrrolic H), 8.96 and 9.05 (AB, 4 H, pyrrolic H); visible A, 436 nm (e 114000), 562 (8300), 600 (11 700), 650 (7 300). Anal. (C52H37N4C104+ CH2C1,) C, H , N . Preparation of Metallo-N-phenyl-meso 4etraphenylporphyrin’s36,39, and 40. Copper complex 36 was obtained (as above from cobalt) from 41 and Cu(OAc), [visible A, 456 nm (c 115600), 554 (10 IOO), 600 (9400), 670 (4 100). Anal. (C50H33N4C104C~) C, H, N]. Metalation of 41 with FeCI2 according to Lavallee et gave 38 whose spectral data are identical with those described in the literature.loc The nickel complex 39 was isolated as its perchlorate following the usual procedure [visible A,, 448 nm (c 81 IOO), 562 (7 500), 625 (7000), 688 (4400). Anal. (CSOH3,N4CINi)C, H, N]. The manganese complex 40 was prepared by using Adler’s procedure39 (Mn(OAc), in refluxing DMF) [visible: ,A, 452 nm (e 120000), 580 (6700), 642 (11 400), 690 (8400). Anal. (CS0H3,N4CIMn)C, H, N]. The cyclization conditions described above for the preparation of 33 were applied to 36-41. Only 40 gave 10% 33. One-Step Preparation of 33. A solution of ClCoTPP (100 mg, 0.14 mmol) and ABTga (200 mg, 1.5 mmol) in 1,1,2,2-tetrachloroethane(4 mL, filtered through a bed of alumina) was heated under dry air at 100 OC for 3 days. Workup as above gave 33 (35 mg, 29%) and 29 (18 mg, 16%). When the same reaction was run in the presence of tetraphenylcyclopentadienone (3 mmol), no spot (TLC) corresponding to TPN could be detected (We checked that when ca. 10 pL of a 2 X 10“ M solution of T P N was deposited on TLC, a faint spot was still visible under UV light; this corresponds to ca. 2 X 1O-I mg). Two major colorless compounds whose polarity was between those of the ketone and the porphyrinic products could be crystallized. They were not fully characterized, but M S and N M R spectra indicated a composition corresponding to ketone + ABT - H,. The same products formed when the reaction was run in the absence of CICoTPP. Electrochemical Measurements. To obtain half-wave potentials we used a Bruker E 130 apparatus equipped with three electrodes: Pt rotating electrode (Tacussel, area 3.4 mm2, 0-5000 revemin-I), a Pt wire as counter electrode, and a calomel reference electrode (in saturated aqueous KCI) connected to the electrochemical cell by a bridge containing the solvent and the supporting electrolyte. The coulometric experiments were run by using a SOLEA 100 1X potentiostat. The electrode was a Pt grid, and the counter electrode was isolated from the solution by a fritted glass. The solvents were of the highest commercially available quality, and the supporting electrolyte, n-Pr4N+CIO4-(0.1 M), was recrystallized from ethanol and dried for 2 days at 80 OC under vacuum. All operations were run under a dry argon atmosphere. At the end of the electrolyses the solutions were washed (H20, 6 times by using 3 X the volume of the organic phase), dried (Na,SO,), and submitted to the normal isolation procedure. The ESR measurements were performed at -196 OC in 1,2-dichloroethane + 0.1 M n-Pr,N+CIO,- (electrolysis medium) by using a Bruker ER 420 spectrometer. The signal observed for 29 showed g = 2.0035, width 68.5 G. Phenylene-Bridged OEP 43. N-PhOEP1IC(35 mg, 0.05 mmol) was quantitatively metalated with Co(OAc),, and the complex was isolated as its perchlorate which was immediately electrolyzed in 1, I ,2,2-tetrachloroethane (50 mL + 0.5 g n-Pr4N+C1O4-)at 120 OC for 44 h. The solution was heated at 120 OC for a further 30 h. After cooling, the usual isolation procedure was followed to yield 43 (1 mg, 3%): ‘H N M R d ca. -4.5 (br signal, 1 H , NH), 1.72, 1.85, 1.88, and 1.98 (4 t, 24 H , CH,), 1.96 and 4.25 (AA’XX’, 4 H, bridge C6H4), 3.9-4.55 (m, 16 H, CH,), 10.06, 10.85, and 10.89 (3 s, 2 + 1 + 1 H, meso); visible A, 410 nm (! 77 600), 542 (6 700), 576 (8 700), 624 (2 500); MS (chemical ionization, NH3), m/e = 609 (M - CIO,). Collection and Reduction of X-ray Data for 13. Crystals suitable for X-ray diffraction studies were obtained from slow diffusion of hexane into

+

(39) Adler, A. D.; Longo, F. R.; Kampas, F.; Kim, J. J . Inorg. Nucl. Chem. 1970, 32, 2443-2445.

J . A m . Chem. SOC.,Vol. 109, No. 10, 1987 2955 a CH,C12-chlorobenzene solution at room temperature. A crystal with dimensions 0.14 X 0.16 X 0.22 mm was sealed in a Lindemann glass capillary and mounted on an Enraf-Nonius CAD4 diffractometer. A summary of crystal and intensity data is presented in Table IV. The automatic locating and centering of 25 reflections (17 < 0 < 29’) followed by least-squares analyses of the setting angles produced accurate unit cell parameters, indicating triclinic crystal system. The Pi space group was confirmed by the subsequent refinement of the structure. A unique set of diffraction data was collected (Cu K a radiation, graphite monochromator). The intensities of three standard reflections were measured every 2 h of X-ray exposure time, and no decay was observed. The intensity data were processed as described in CAD4 and SDP-PLUS User’s The net intensities and their standard deviations were corrected for Lorentz-polarization effects. An empirical absorption correction was applied by use of $ scans for x values near 90’. The maximum, minimum, and average transmission factors obtained are 1.OO, 0.92, and 0.97, respectively. Solution and Refinement of the Structure. The structure was solved by direct methods. A total of 56 out of 73 non-hydrogen atoms were found on the best E map. From a three-dimensional electron density map, the positions of 14 more atoms were obtained. Subsequent structure factor calculations and Fourier syntheses revealed the position of the remaining non-hydrogen atoms. The atomic scattering factors were taken from the usual tabulation$1aand the effects of anomalous dispersion were included by using Cromer and 1bers’Ilb values of Af’ and Af”. The chlorobenzene molecule resides on a position of 7 symmetry, and its chlorine atom CIS was treated as two half atoms. Some difficulties were encountered with the dichloromethane molecule, in which one chlorine atom appeared disordered. Refinement was conducted with a model in which this chlorine was refined as three third atoms: C12, C13, C14. The observed values for the angles CII-C-Cln (n = 2, 3,4) are near 109’ ( 1 12.4 ( 6 ) , 105.0 (6), 113.2 (7)O). The non-hydrogen atoms of the dichloromethane molecule were refined isotropically, while all other non-hydrogen atoms including those of the chlorobenzene molecule were refined anisotropically. The function minimized was Cw(lFoI - lFc1)2, where IF,! and lFcl are the observed and calculated structure amplitudes and w = 1/ [ C ( F , , ) ] ~After . successive full-matrix least-squares refinement cycles, the positions of the hydrogen atoms, except those of the hydrogens on the dichloromethane molecule and of the proton on the porphyrin nitrogen atom, were calculated and verified on a difference Fourier synthesis. They were introduced with fixed idealized geometry (C-H = 0.95 8, and B = 5 A2)but not refined. Further cycles of refinement yielded Rl = 0.074 and R, = 0.096. At this stage, a difference Fourier synthesis map revealed two peaks, located 0.9 A from N 3 and N4, respectively. Both were introduced as hydrogen with B = 5 A2 and an occupancy of a half and not refined. The final refinement converged to values of R1 and R2 of 0.067 and 0.087, respectively. The final values of the positional parameters, anisotropic thermal parameters for nonhydrogen atoms, and a listing of the observed and calculated structure amplitudes are available as Supplementary Material.42

Acknowledgment. We thank the C.N.R.S. for financial support. B.M. is grateful to Dr. D. Moras for his hospitality. Supplementary Material Available: Listings of positional parameters, anisotropic displacement parameters for non-hydrogen atoms, and a table with least-squares mean planes for (C58H39N4)(C104)-(CH,CIJ.’/,( C6H5CI)(6 pages); listing of observed and calculated structure factors ( 2 2 pages). Ordering information is given on any current masthead page. (40) All crystallographic work was done at the Laboratoire de Cristallographie Biologique, I.B.M.C. du C.N.R.S. Instrumentation consists of an Enraf-Nonius CAD4 diffractometer controlled by a DEC PDP 8/A with a RLOl disk. The Enraf-Nonius software used is described in CAD4 Operation Manual; Enraf-Nonius: Delft, Amsterdam, 1977 (updated in Jan 1980). All calculations were carried out on a DEC PDP 11/44 equipped with three disk drives (a RM02 and two RL02 disk drives), a Versatec printer/plotter, and a Plessey Kennedy 9000 tape drive with the use of the Enraf-Nonius CADISDP-PLUS programs. This crystallographiccomputing package is described by: Frenz, B. A. In Computing in Crystallography; Schenk, H., Olthof-Hazekamp, R. O., van Konigsveld, H., Bassi, G . C., Eds.; Delft University Press: Delft, Holland, 1978; pp 64-71. Frenz, B. A. In Structure Determination Package and SDP-PLUS User’s Guide; Frenz, B. A. & Assoc., Inc.: College Station, TX, 1982. (41) (a) Cromer, D. T.; Waber, J. T. International Tables for X-ray Crystallography; Kynoch: Birmingham, England, 1974; Vol. IV, Table 2.2B. (b) Cromer, D. T.; Ibers, J. A. International Tables for X-ray Crystallography; Kynoch: Birmingham, England, 1974; Vol. IV, Table 2.3.1. (42) Supplementary material, see paragraph at the end of this paper.